SIMS study of TiN carbon implanted at high-fluences

Abstract

Ion implantation of titanium nitrite (TiN) coatings attracts a great deal of attention because of the improvement of tribological resistance of the coating surface.In this work we have analysed implanted TiN films by using secondary ion mass spectrometry (SIMS). Coatings with a thickness of about 4 μm were implanted with C+ at energies of 100 keV and fluences ranging from 1016 to 7×1017 ions/cm2. The experiments were performed on commercial TiN films prepared by physical vapour deposition (PVD) on hard metal tools.If reactive elements, like C or N, are implanted to significative fluences, the implant concentration (say greater than 1 at.%) could induce a distortion in the experimental elemental profiles because of a change in the sputtering yield and/or the ionisation probability (matrix effects). While the first point has been shown to be largely insignificant, the second is studied in more detail. In the case of carbon implanted in TiN the influence of matrix effects on the secondary ion signals can be minimised if a primary beam of Cs+ and secondary negative ions are chosen for depth profiling up to fluences of technological interest, say 3×1017 ions/cm2. In this way the concentration changes induced in the ion implanted region can be quantified. Linear calibration curves were obtained for an accurate quantification and X-ray photoelectron spectroscopy (XPS) was employed to extract the starting stoichiometry in the unimplanted TiN film and to assess the chemical state along the depth profiles in the implanted samples. After implantation a swelling of the films was observed and has been discussed. SIMS profiles were measures both by cesium and oxygen primary beams.